Kinematics of a Novel Type Positioning Table for Cast Alignment on Machine Tool

2015 ◽  
Author(s):  
Adam Myszkowski ◽  
Tomasz Bartkowiak ◽  
Andrzej Gessner
Keyword(s):  
Machine Tool ◽  
Parallel Mechanism ◽  
Heuristic Methods ◽  
Rotary Table ◽  
Geometrical Constraint ◽  
Sphere Center ◽  
Linear Actuators ◽  
Leg Design ◽  
Geometrical Dimensions

The paper presents a study into the kinematics of a novel type of a rotary positioning table based on the constrained parallel mechanism. Fixture and leveling a workpiece on a machine tool table is an essential stage in machining or layout process. In this study, a compact low-height rotary table is presented for automated leveling, which can be mounted directly on the machine tool table without a significant decrease of the workspace. The authors propose a modification of parallel mechanism by introducing four extensible leg design with specific geometrical constraint for workpiece positioning and in order to achieve higher rigidness. The table is driven by four hydraulic linear actuators which are integrated in the linkages. The designed model allows to rotate the table about the sphere center about three independent axis. Procedures using meta-heuristic methods were implemented to optimize the geometrical dimensions of the entire mechanism for the required workspace.

Error Comparison and Analysis of Parallel and Constraint Mechanism for 3-TPS Hybrid Machine Tool

2011 ◽  
Vol 127 ◽  
pp. 277-282
Author(s):  
Peng Fei Dang ◽  
Li Jin Fang
Keyword(s):  
Machine Tool ◽  
Parallel Mechanism ◽  
Parallel Robot ◽  
Error Model ◽  
Position Error ◽  
Robot Kinematics ◽  
Motion Error ◽  
Movable Plate ◽  
Hybrid Machine Tool ◽  
Hybrid Machine

This paper establishes position error model based on parallel robot kinematics theory, and analyses position error of the 3-TPS hybrid machine tool. Firstly, to calculate position error of the movable plate caused by the parallel mechanism links, through error model of the parallel mechanism which is established through inverse kinematics of the hybrid machine tool. Then, according to the error model of constraint mechanism established by transformation matrix method, the position error has been simulated and calculated. Finally, this paper compares the effects of both mechanisms. The analysis indicates the link error of constraint mechanism has more influence on movable plate posture than parallel mechanism, and provides help with motion error compensation and kinematic calibration.

scholarly journals Modelling and Simulation of Machine Tool Prototype with 6DOF Parallel Mechanism in Matlab / Simulink

2019 ◽  
Vol 254 ◽  
pp. 03002 ◽  
Author(s):  
Vladimír Bulej ◽  
Juraj Uríček ◽  
Manfred Eberth ◽  
Ivan Kuric ◽  
Ján Stanček
Keyword(s):  
Machine Tool ◽  
Simulation Model ◽  
Mechanical System ◽  
Parallel Mechanism ◽  
Control Algorithms ◽  
Kinematic Structure ◽  
Matlab Simulink ◽  
Parallel Kinematic ◽  
Functional Blocks ◽  
Functional Prototype

The article deals with the preparation of simulation model of mechanism with parallel kinematic structure called hexapod as an electro-mechanical system in software MATLAB/Simulink. The simulation model is composed from functional blocks represented each part of mechanism’s kinematic structure with certain properties. The results should be used for further simulation of its behaviour as well as for generating of control algorithms for real functional prototype.

Kinematics Analysis of a New 5 DOF Parallel-Serial Machine Tool Based on the Vector Method

2010 ◽  
Vol 450 ◽  
pp. 283-287 ◽  
Author(s):  
Rui Wang ◽  
Gang Ding ◽  
Shi Sheng Zhong
Keyword(s):  
Machine Tool ◽  
Parallel Mechanism ◽  
Kinematics Analysis ◽  
Vector Method ◽  
Velocity Transformation ◽  
Axis Parallel ◽  
Movable Platform ◽  
Parameter Coupling ◽  
The Relationship ◽  
Kinematics Parameters

A 5-axis parallel-serial machine tool is proposed, which consists of a 3-DOF parallel mechanism and a 2-DOF serial mechanism, and the kinematics analysis is discussed in detail based on the vector method. The size of the velocity transformation matrix is decreased. The problem of parameter coupling is resolved by adopting identity matrix and four-element vector. The relationship between the velocity and acceleration of the movable platform and the input parameters of the parallel mechanism is established. These algorithms are verified correct through ADAMS (Automatic Dynamic Analysis of Mechanical System) and can be referenced by kinematics analysis, dynamics analysis of parallel or parallel-serial machine tools, which have coupling kinematics parameters.

Kinematic Calibration for Redundantly Actuated Parallel Mechanisms

2004 ◽  
Vol 126 (2) ◽  
pp. 307-318 ◽  
Author(s):  
Jay il Jeong ◽  
Dongsoo Kang ◽  
Young Man Cho ◽  
Jongwon Kim
Keyword(s):  
Optimization Algorithm ◽  
Parallel Mechanism ◽  
Kinematic Calibration ◽  
Parallel Mechanisms ◽  
Geometrical Constraint ◽  
Kinematic Parameters ◽  
Angle Error ◽  
Calibration Algorithm ◽  
Redundantly Actuated

We present a new kinematic calibration algorithm for redundantly actuated parallel mechanisms, and illustrate the algorithm with a case study of a planar seven-element 2-degree-of-freedom (DOF) mechanism with three actuators. To calibrate a nonredundantly actuated parallel mechanism, one can find actual kinematic parameters by means of geometrical constraint of the mechanism’s kinematic structure and measurement values. However, the calibration algorithm for a nonredundant case does not apply for a redundantly actuated parallel mechanism, because the angle error of the actuating joint varies with position and the geometrical constraint fails to be consistent. Such change of joint angle error comes from constraint torque variation with each kinematic pose (meaning position and orientation). To calibrate a redundant parallel mechanism, one therefore has to consider constraint torque equilibrium and the relationship of constraint torque to torsional deflection, in addition to geometric constraint. In this paper, we develop the calibration algorithm for a redundantly actuated parallel mechanism using these three relationships, and formulate cost functions for an optimization algorithm. As a case study, we executed the calibration of a 2-DOF parallel mechanism using the developed algorithm. Coordinate values of tool plate were measured using a laser ball bar and the actual kinematic parameters were identified with a new cost function of the optimization algorithm. Experimental results showed that the accuracy of the tool plate improved by 82% after kinematic calibration in a redundant actuation case.

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